Radio Days

Viral Communications


Following the 2016 election, the entirety of the nation became conscious of its polarization. According to a study by the National Bureau of Economic Research*, polarization has increased among Americans since 1990. The study observes, however, that in eight of the nine measures of polarization, older individuals (70+ age group) show higher rates of increase in polarization than other age groups. This age group also utilizes social media less than other age-groups. Could it be that social media is not the root cause of polarization?

In order to explore this further, we looked at polarization through talk radio, which is commonly thought to have political influence. 

"Talk radio’s potency in primary elections derives from hosts’ special relationship with listeners. Listeners consider hosts to be friends who share their sensibilities and worldviews—after all, they spend hours together each week. So listeners take a call to action from a host as seriously as they might if a friend or family member encouraged them to act. “ 

— Brian Rosenwald, author of Mount Rushmore: The Rise of Talk Radio and Its Impact on Politics and Public Policy.

Talk radio is a platform that's often overlooked during media analysis. It’s harder to track than digital platforms such as Twitter. Furthermore, stations pop up in rural and hard-to-reach areas.

The best available data on talk radio we found is kept by Nielsen, which offers this data for advertisers. Nielsen captures listenership data on a talk-radio market by assigning listening devices to a sampling of individuals in this market. This data is not without controversy*.

The Nielsen top-line rating data provide measurements of the share of listenership for every radio station in 260 radio markets across the USA. The data-sets also contain population information for the markets. The smallest market tracked has a population of 79,000 people.

We set about labeling each talk-radio station as either liberal or conservative depending on which shows it hosts. Since there is no TV Guide for radio, we collated information from radio-show listings for Rush Limbaugh and NPR. We found little overlap in the stations of these two shows. By labeling these talk radio-stations as left-leaning or right-leaning, we were then able to create a score for each market. For example, if a market in Boston had a majority of its listenership being dedicated to liberal stations, it would have a high liberal score.

The 2D maps below show the Nielsen Top Line Ratings data for listenership. The bubbles represent radio markets that are tracked by Nielsen. The size of the bubble represents the population of listeners in the market. Each bubble is interpolated between red and blue, indicating the percentage share of conservative talk radio stations in the market. The counties are colored based on unemployment in the USA.

The first map shows the markets with a majority of hours listened to conservative stations. These markets are smaller and more disbursed across the nation.

The second map shows markets with a majority of hours listened to liberal stations. They are larger and more concentrated in big cities.

The final map shows both the conservative and liberal markets together. You can play with the data at: and see the code at:

+ Boxell, Levi, Matthew Gentzkow, and Jesse M. Shapiro. "Greater Internet use is not associated with faster growth in political polarization among US demographic groups." Proceedings of the National Academy of Sciences (2017): 201706588.